GOSSEN LUNA-PRO / LUNA-PRO FLEXIBLE FIBER PROBE OPTICS ATTACHMENT User manual

GOSSEN
   Luna'Pro
     and
  Lulra'Pro sbc

 Flexible Fiber
  ProbeOptics
  Attachment



  Instruc$ilOns

The Fiber Optics attachment for your      transparencies, contrast measurements,
 Luna-Pro or Luna-Pro sbc allows you to     and other lu m inous density measurements
 make light measurements not normally       with your Luna-Pro or Luna-Pro sbc.
 possible with an ordinary meter. Very small
 objects, or specific areas of larger subjects      Note: Before reading the following detailed
 can be easily measured with this probe. In      instructions, you should be completely
 addition, the Fiber Optics attachment  is      familiar with the general operating pro-
 ideal   f or g rou nd g lass measu rements,     cedures outlined in the Luna-Pro or
 density measurements on negatives and      Luna-Pro sbc owner's manual.



ATTACHING TO THE METER
A. Slide the spherical diff user of the  1-
   Luna-Pro or Luna-Pro sbc to the right so
   that it will fit into the cavity of the
   attach ment.
B. Insertthe lug (2, Fig. 1) of the probe into
  the slot at the front of the meter   housings.                                         ffi"^f$i*q,.
C. While pressing the locking knob (1,
   Fid. 1) slide the probe flush into the
   meter (the diff user of the meter  f its into
   the recess of thq aC rpter. ) Releasing the
   locking knob will fasten the probewww.butkus.usin
    p lace.
                                                                                Figure 1

Calibrating Camera Ground Glass for           lens. For convenience in reading, after
Through the Lens Measurements               focusing, stop the lens down to the first
                                                              full stop from maximum aperture.The Fiber Optics Probe allows readings to
be taken on a camera ground glass. The     Now take a reading directly from the grey
advantage of this method is that exposure       card, not through the camera back, using
modifying factors such as  f ilters, extension       the probe. When using the Luna-Pro, the
factors, etc., are corrected for because the       scale reading should be set opposite the
reading is taken after these modifying       green indicator on the computer dial. With
agents. Therefore, any effect they have will     the Luna-Pro sbc, the meter is used
be read by the meter.                            normally. The ASA setting of the meter is
                                                unimportant as long as it is constant duringBefore using the Fiber Optics Probe with
the camera ground glass, a reading index       the procedure. Note lhe exposure time that                                                                        is opposite the  f /stop you previously set onmust be determined. This is because the                                             your camera lens.ground glass  f urther modif ies the light past                                           frujtw,r/)the  f ilm plane. This change in light, which                                                 Next, take a reading of                                                                        the grey card off thethe film does not see, must be compen-                                         camera ground glass, making sure that nosated for.                                                  stray light strikes the back of the glass. A
To determine a reading index for your      dark focusing cloth is helpful for this
camera, set up your camera facing an 18oh      purpose. Note the f/stop that appears
grey card. Use of an 18% grey card will      opposite the exposure time determined
calibrate for an average scene as described      when reading the grey card directly. This is
in the Method of Measurement section in      your reading index which will be used to
the Luna-Pro sbc instruction manual. When      determine new exposure times for any
setting up the camera, center the grey card      combination of lighting, subjects, film
in the ground glass and get far enough back      speed, filters, extension factors, etc., as
so that you do not have any appreciable       long as the same ground glass is used. For
extension factor. The camera should bewww.butkus.usin       future reference, mark this index with one
the neutral position with no filters on the        of the stickers supplied. When changing to

another ground glass, this index will have        correction dial of the Luna-Pro sbc until the
 to be checked, and possibly corrected.          shutter speed setting determined when
                                                 reading the grey card direcily comes back Note that this index has nothing to do with
 the aperture set on the lens. lt is only an      on scale. Then record both the new reading                                              index and exposure correction setting as index.                                             your final reading index.
 Example: Yourcamera lens has a maximum
aperture of   f /6.3. After focusing, your     When working with a twin lens camera, the
aperture would be set to f/8, the first full       procedure is the same except that you will                                     not be able to stop down from yourstop that your lens has after its maximum
aperture of f/6.3. A direct reading of the     maximum aperture. In this case read the
grey card with the Luna-Probe gives an        direct grey card exposure time opposite the                                        stop that equals the aperture of yourexposure time of 1/60th of a second at  f /8,
the aperture you set on your camera. You       camera's viewing lens. Next measure the                                           grey card through the ground glass andnow measure the grey card through the                                       read opposite the exposure time justground glass. Reading opposite 1/60th of a                                              determined in the previous sentence. Thesecond,             shutter       the                 speed                          that                                was                   f /stop indicated will be your reading index.indicated                                     reading         opposite                 when                                                          t /8
directly off the grey card, you now  f ind an
aperture of t/1.  f /1 is your reading index.
For most cameras, your reading index will       Reading Through the Ground Glass
be around  f /2.8 with the Luna-Pro and  f /1      There are two ways to take a reading
with the Luna-Pro sbc regardless of what       through the ground glass, stopping down
your lens' maximum aperture is. lf, in the       to working aperture or with the lens wide
unlikely event with the Luna-Pro sbc, your     open. In both cases, you must first
ground glass is so dense that your reading       determine a reading index as previously
index goes below  f /0.7, the lower limit of       described, and set the film speed being
the Luna-Pro sbc scale, rotate the exposure      used into the meter.

Reading at Working Aperture                  Reading at Full Aperture
Compose and focus your camera. Place a      For maximum accuracy, it is preferable to
grey card in the area to be measured. Stop      meter at working aperture. However, with
down the lens to your desired working      some cameras, this may not be.possible.
aperture. Place the Fiber Optics Probe on      For example, the ground glass in a twin
the ground glass over the grey card area.       lens reflex camera receives its illumination
Make a measurement and read your      from the viewing lens, not the taking lens.
exposure time opposite the reading index.       Since there is no diaphram on this lens, the
Remember to use the green index with the        light level through the viewing lens striking
Luna-Pro.                                  the ground glass cannot be adjusted to
                                          match the light level that will reach the  f ilmlf you wish to work at an exposure time       plane. In this case, the calculator dial of theother than the one indicated opposite the                                             Luna-Pro or Luna-Pro sbc can be used as areading index. you have several options.                                          convenient guide to determine new ex-
1. Set the desired exposure time opposite      posure time-f /stop combinations. This     ?  the reading index and vary the lens      method works as follows:
  aperture until the meter indicates the        1. Take your measurement at maximum  number opposite the green index with          aperture and read opposite the reading     l                       with      Luna-Pro                          the   the               or null                                Luna-Pro       index.                                  A */<t    i. a 5                        grey                                  card.       while reading                    the  sbc                                                 2. Rotate the computer dial until the
2. Calculate the numberof stops difference         exposure time indicated by the reading   between the indicated exposure time and                                                   index is opposite the maximum aperture   the desired time. Adjust your  f /stop by                                                    of the measuring lens. Do not confuse
   the same number of stops.                      this step with taking a reading. The
3. Use the meter's calculator dial as de-          calculator is being used only as a guide.
   scribed in the section Reading at Full        The meter does not have to be at null in   Aperture.                   www.butkus.usthis step.

3. Read any combination of  f /stop-shutter       Note: Depending on the camera lens and
  speed you desire  f rom the calculator dial.     ground glass used, various measuring
                                                                                                                                                                                                                            f urther   Example: Your film speed is 100 ASA.       errors can occur as you start to read
   Your reading index yields an exposure      out towards the edge of the ground glass.                                 You can measure this light fall off by   time of 1 / 125tn of a second when a mea-                                            pointing the camera towards a neutral,   surement is taken through your viewing                                          evenly lit wall and measuring the light    lens that has a maximum aperture of t/4.
   Rotate the calculator dial until the       intensity of the ground glass image at the                                                 center and at other points toward the edge.   1/125th second mark lines up opposite
         f /4. The calculator dial will now indicate    You should take these deviations into
   times such as 1/8th second at t/16,     account when making exposure determina-
     1 /1sth second at f/1 1, 1 /30th second at      tions off axis.
   f/8, etc. Choose the combination you
   want and set it in the camera.

the  f ilm can be calculated from the formula       allow you to convert the meter readings into
D - 0.3 (EV1    EVZI. Each change of one       the approximate luminance values. To use,EV equals a density-    change of 0.3. The 1/3       set the film speed scale to 50 and take a
EV marks on the dial are equivalent to a      reading of your subject. Note the EV
density change of 0.1.                          reading and find the luminance value from
To measure the density range of the      the table.
negative,  f irst take a reading of the lightest                                                   Scale
                                      asarea            negative                EV                     and read     of the                    in                                             Value                                       IEVI Nlts [cdm'2]EVmax.            measure       Next                                 area                          darkest                                           of                     the                                   -5                                             .06FL [tf -1 cd lt.018-2]the negative and read as EV6i1.              -4          .12             .035The density range can be calculated from       -3          .24           '     .07
                                                                                                    .14the formula D = (EVmax   EVmin.).       -2          .48These density values can then be used to       -1          .95             .28determine paper grades when making      0         1.9               .55photographic prints,  determining the      1         3.8              1.1necessity for making masks, etc.           2         7.5             2.2                            3       15               4.5LUMINANCE                            4309Lum inance measurements can be made      5       60             18with the Fiber Optics Probe. When taking a      6      120           35reading, be sure not to cast a shadow on the      7      240           70area measured. For accurate readings, the            I       480          140area being measured should be uniform.      9      950          280Luminance values can be determined for      10            1 ,900          550both the metric and English systems. For      11     3,800        1,100metric measurements, the readings will be      12     7,500       2,200in nits or cdm-z. For English measure-      13    15,000       4,500ments the readinos will be in footlamberts      14    30,000       9,000or fl -1 cdft.-2.-g chart follows that will      15    60,000      19,000                            16    120,000     35,000

TECHNICAL INFORMATION
The Fiber Optics Probe conslsts of
approximately 4,000 glass  f lbers of around
0.07 millimeters diameter each. A small
plastic support ralses the probe end
slightly from the surface of the obJect or
ground glass being measured, preventing
scratch ing.
Length  ,....    r..  r..   I r r..  r. r...  r.400mm
Measuring Aperture  . .5mm diameter equq!
                    to approxi mately 1 9.6m mz
MgasurlngAngle ....  . . . . ...  . . ...,.,32o

CARE OF YOUR FIBER OPTICS PROBE
Only the flnest materials are used in your
Fiber Optlcs Probe. However, the  f ibers in
the probe can be damaged  if subJected to
abuse. Breakage of the fibers will cause
loss of eff iciency, affecting the calibration
of the probe.
Reasonable care should be exerclsed when
using the Fiber Optics Probe. Do not
subJect it to abnormal stress, bend  it at very
sharp angles, or allow objects to strlke or   Angle sensitivity of measuring probe attachment
rest on the probe.  lf service is ever required,
take it to your dealer or send it to the
address shown on the back of this booklet.